function ajax(url,id) {																										
	var httpObj = false;																											
		httpObj = window.XMLHttpRequest ? new window.XMLHttpRequest : (window.ActiveXObject ? new ActiveXObject("MSXML2.XMLHTTP"): null);
		httpObj.onreadystatechange = function() {																		
		if (httpObj.readyState == 4) {
			if(id=="email"){
				document.getElementById("imgemail").style.visibility=httpObj.responseText;
				formCheck("email");
			}
			else {
				document.getElementById(id).innerHTML = httpObj.responseText;
			}
			return;																											
		}																														
	};																															
	httpObj.open('POST', url, true);																					
	httpObj.send(null);																										
}
var num=0;
function formCheck(id){
	if(id!="email"){
		input = document.getElementById(id);
		if(input.value != "") document.getElementById("img"+id).style.visibility='visible';		
		else document.getElementById("img"+id).style.visibility='hidden';
	}
	if (
		(document.getElementById("naam").value != "") && 
		(document.getElementById("voornaam").value != "") && 
		(document.getElementById("adres").value != "") && 
		(document.getElementById("postcode").value != "") && 
		(document.getElementById("plaats").value != "") && 
		(document.getElementById("imgemail").style.visibility != "hidden") && 
		(document.getElementById("vraag").value != "")
	   ) 
	   	{
			document.getElementById("knopje").disabled = false;
			document.getElementById("melding").style.visibility = 'hidden';
	}
	else {
		document.getElementById("knopje").disabled = true;
		document.getElementById("melding").style.visibility = 'visible';
	}
}